Although it may be a bit more complicated since you're making a modification of my branch, instead of Hadley's master branch. If that ends up being too much trouble, you can just cut/paste the patch here.

The problem with this approach is that it doesn't allow for other labeller functions. To really fix this we need a more flexible specification of labeller functions - they should take a matrix (or other richer data structure) as an argument. But this will mean that we need to rewrite the existing labeller functions and hence is an API breaking change, which means we need to push it off to a future version.

Same here. This doesn't seem to have been fixed. writing a (variable-specific) labeler function every time I'd like to relabel facets seems tedious. Sorry, if this has been fixed and I missed it. cheers.

This sounds like a great feature, but unfortunately we don't currently have the development bandwidth to support it. If you'd like to submit a pull request that implements this feature, please follow the instructions in the development vignette.